Session PB7.3

Volumetric Measurement of the Anatomic Regurgitant Orifice Area in Mitral Regurgitation

S Chandra, L Weinert, L Sugeng, IS Salgo, SH Settlemier,
JX Shen, RM Lang, V Mor-Avi*

University of Chicago
Chicago, IL, USA

Aim: Mitral effective regurgitant orifice area (EROA) using the flow convergence (FC) method is the current method of choice for quantifying the severity of mitral regurgitation (MR). However, this methodology has limitations, especially in patients with complex mitral valve (MV) pathology. The superior image quality of the transesophageal real-time 3D echocardiography (RT3D-TEE) offers an opportunity for direct visualization and 3D measurements of the anatomic regurgitant orifice area (AROA), independently of confounding hemodynamic variables in both primary and secondary MR. We developed software for quantitative volumetric measurement of anatomic AROA, which takes into account its complex 3D geometry, rather than using planimetry in a single cut-plane. The goals of this study were: (i) to use this software to quantify AROA in patients with moderate to severe MR, (ii) to compare volumetric AROA values to conventional 2D FC measurements, and (iii) to compare the reproducibility of these two techniques.
Methods: We studied 67 subjects, undergoing clinically indicated TEE, with well visualized FC, including 19 patients with primary (degenerative) MR, 19 patients with secondary (i.e. functional) MR of either ischemic or dilated etiology, 20 patients with no significant MR, and 9 patients with primary MR and highly eccentric, non-hemispherical, distorted FC especially challenging for FC measurements, who were studied separately. EROA calculations were obtained from 2D TEE images using FC technique, while AROA was measured from zoomed RT3DE-TEE acquisitions using prototype software for direct volumetric orifice area measurements. Inter-technique comparisons included linear regression and Bland-Altman analyses.
Results: Volumetric analysis allowed successful definition of the coaptation line in all 20 patients with normal valves. In patients with MR, measurements of regurgitant orifice area correlated well between techniques (r=0.92) and showed only a non-significant positive bias (0.04 cm²). However, in primary MR group, the bias was larger than in secondary MR group (0.05 cm² and 0.03 cm², respectively), and the limits of agreement were more than twice that in secondary MR (SD: 0.16 vs 0.07 cm²). In the 9 patients with highly eccentric non-hemispherical FC, there was considerable discrepancy between FC measurements of ERAO and volumetric AROA, resulting in inter-technique difference was 42±18% of the mean of the two techniques, compared to 20±17% in the main study group of 38 patients with MR. Inter-measurement variability of the FC technique was higher than that of the RT3DE-based measurements.
Conclusions: Visualization of the true anatomic MV orifice from RT3DE-TEE images is feasible in most patients. With its superior reproducibility, volumetric analysis of these images may become a useful alternative to quantify MR in patients in whom EROA measurement by FC technique is challenging.

(Abstract Control Number: 191)